In Austin I am dealing with sidewalk construction/tree damage issues. The ADA has complicated this
somewhat with the stringent design criteria. I am interested in any viable
and cost effective techniques that any of you have observed, or maybe even helped to design.

I am also on the city's Urban Forestry Board so this is particularly important as something
that can become a standardized approach to dealing with this conflict.

Typical scenario is that a street and curb, with wheelchair ramp, have been previously installed (impact #1). COnstruction may
be occuring on the property (impact #2) and then then the city requires the contractor to build
a typical sidewalk transversing the tree on two sides. Typical specifications require a sub grade base for the sidewalk to be
built on. The most obivous solution would be to bridge as much root zone as possible. Bridging with suitable, ADA suitable, surface is tricky.

Anyway, just tossing out a plea here. Anyones ideas are welcome! Please email me, as well as post here.

Thanks,

Dennis Brown
Austin, TX

Reply to post by Dennis Brown, on October 13, 1998 at 15:04:41:


Dennis,

Unfortunately, your 2nd paragraph speaks to the real issue in such cases - there simply are no absolutes. It seems especially frustrating to engineers and public works folks that there isn't a "standard" solution. Each tree conflict represents a unique set of factors. The tricky part is recognizing them and then applying a solution based upon those factors.

There are many options out there. Bridging, structural soils, ramping, sidewalk elimination, tree elimination (gasp) and other methodologies are all applicable in specific circumstances.

The best thing you can do is have someone on the ground who is capable of making those determinations from a professional standpoint.

Maybe not much help, but as Cronkite used to say "That's the way it is".

Steve Shurtz
Baton Rouge, LA

Reply to post by Dennis Brown, on October 13, 1998 at 15:04:41:

Dennis,

With one architect client we were able to spec an ADA ramp into a public structure with point footings (piers) rather than a continuously excavate footing across a root zone. The sidewalk leading up to the ramp was relatively farther from the critical root zone, but I think we specced some sort of installation above existing grade with a shallow or no subbase, but this was onsite, not the streetside walk. The extra work was all required because the tree was historically designated.

One of my municipal clients will use asphalt to ramp over tree roots in some secondary areas rather than excavating, installing new subbase and pouring new concrete (repair situations).

Our tree board has been asked for advice from time to time and we've suggested that neighborhoods or blocks be involved in the decision process and advised that if they want new spiffy sidewalks they may lose trees. Sometimes the trees win and they stop pushing for the sidewalk work. The Environmental Protection Board has started refusing to approve certain Public Works projects if the trees are adversely affected and the work is not necessary for public safety (as in let's do it because the Feds will give us the money).